7f0ef7ad59
* spot/twaalgos/genem.cc, spot/twaalgos/genem.hh: Improve the worst case by not recurring twice into each disjunct individually. Keep the previous two implementation available and add a function generic_emptiness_check_select_version() so we can benchmark the difference. * tests/python/genem.py: Test the three versions.
225 lines
7.2 KiB
C++
225 lines
7.2 KiB
C++
// -*- coding: utf-8 -*-
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// Copyright (C) 2017-2020 Laboratoire de Recherche et Developpement
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// de l'Epita (LRDE).
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//
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// This file is part of Spot, a model checking library.
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//
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// Spot is free software; you can redistribute it and/or modify it
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// under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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//
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// Spot is distributed in the hope that it will be useful, but WITHOUT
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// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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// or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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// License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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#include "config.h"
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#include <spot/twaalgos/genem.hh>
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#include <spot/twaalgos/cleanacc.hh>
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namespace spot
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{
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namespace
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{
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enum genem_version_t { spot28, atva19, spot29 };
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static genem_version_t genem_version = spot29;
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}
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void generic_emptiness_check_select_version(const char* emversion)
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{
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if (emversion == nullptr || !strcasecmp(emversion, "spot29"))
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genem_version = spot29;
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else if (!strcasecmp(emversion, "spot28"))
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genem_version = spot28;
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else if (!strcasecmp(emversion, "atva19"))
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genem_version = atva19;
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else
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throw std::invalid_argument("generic_emptiness_check version should"
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" be one of {spot28, atva19, spot29}");
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}
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namespace
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{
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static bool
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is_scc_empty(const scc_info& si, unsigned scc,
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const acc_cond& autacc, twa_run_ptr run,
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acc_cond::mark_t tocut = {});
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static bool
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scc_split_check(const scc_info& si, unsigned scc, const acc_cond& acc,
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twa_run_ptr run, acc_cond::mark_t tocut)
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{
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scc_and_mark_filter filt(si, scc, tocut);
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filt.override_acceptance(acc);
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scc_info upper_si(filt, scc_info_options::STOP_ON_ACC);
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const int accepting_scc = upper_si.one_accepting_scc();
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if (accepting_scc >= 0)
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{
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if (run)
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upper_si.get_accepting_run(accepting_scc, run);
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return false;
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}
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if (!acc.uses_fin_acceptance())
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return true;
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unsigned nscc = upper_si.scc_count();
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for (unsigned scc = 0; scc < nscc; ++scc)
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if (!is_scc_empty(upper_si, scc, acc, run, tocut))
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return false;
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return true;
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}
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static bool
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is_scc_empty(const scc_info& si, unsigned scc,
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const acc_cond& autacc, twa_run_ptr run,
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acc_cond::mark_t tocut)
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{
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if (si.is_rejecting_scc(scc))
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return true;
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acc_cond::mark_t sets = si.acc_sets_of(scc);
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acc_cond acc = autacc.restrict_to(sets);
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acc = acc.remove(si.common_sets_of(scc), false);
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auto generic_recurse =
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[&] (const acc_cond& subacc)
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{
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int fo = (SPOT_UNLIKELY(genem_version == spot28)
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? acc.fin_one() : subacc.fin_one());
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assert(fo >= 0);
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// Try to accept when Fin(fo) == true
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acc_cond::mark_t fo_m = {(unsigned) fo};
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if (!scc_split_check
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(si, scc, subacc.remove(fo_m, true), run, fo_m))
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return false;
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// Try to accept when Fin(fo) == false
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if (!is_scc_empty(si, scc, subacc.force_inf(fo_m), run, tocut))
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return false;
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return true;
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};
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if (SPOT_LIKELY(genem_version == spot29))
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{
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acc_cond::acc_code rest = acc_cond::acc_code::f();
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for (const acc_cond& disjunct: acc.top_disjuncts())
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if (acc_cond::mark_t fu = disjunct.fin_unit())
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{
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if (!scc_split_check
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(si, scc, disjunct.remove(fu, true), run, fu))
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return false;
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}
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else
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{
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rest |= disjunct.get_acceptance();
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}
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if (!rest.is_f() && !generic_recurse(acc_cond(acc.num_sets(), rest)))
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return false;
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}
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else
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{
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for (const acc_cond& disjunct: acc.top_disjuncts())
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if (acc_cond::mark_t fu = disjunct.fin_unit())
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{
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if (!scc_split_check
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(si, scc, disjunct.remove(fu, true), run, fu))
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return false;
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}
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else
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{
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if (!generic_recurse(disjunct))
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return false;
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}
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}
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return true;
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}
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static bool
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generic_emptiness_check_main(const twa_graph_ptr& aut,
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twa_run_ptr run)
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{
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// We used to call cleanup_acceptance_here(aut, false),
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// but it turns out this is usually a waste of time.
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auto& aut_acc = aut->acc();
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if (aut_acc.is_f())
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return true;
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if (!aut_acc.uses_fin_acceptance())
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{
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if (!run)
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return aut->is_empty();
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if (auto p = aut->accepting_run())
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{
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*run = *p;
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return false;
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}
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return true;
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}
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// Filter with fin_unit() right away if possible.
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// scc_and_mark_filter will have no effect if fin_unit() is
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// empty.
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scc_and_mark_filter filt(aut, aut_acc.fin_unit());
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scc_info si(filt, scc_info_options::STOP_ON_ACC);
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const int accepting_scc = si.one_accepting_scc();
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if (accepting_scc >= 0)
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{
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if (run)
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si.get_accepting_run(accepting_scc, run);
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return false;
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}
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unsigned nscc = si.scc_count();
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for (unsigned scc = 0; scc < nscc; ++scc)
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if (!is_scc_empty(si, scc, aut_acc, run))
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return false;
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return true;
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}
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}
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bool generic_emptiness_check(const const_twa_graph_ptr& aut)
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{
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if (SPOT_UNLIKELY(!aut->is_existential()))
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throw std::runtime_error("generic_emptiness_check() "
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"does not support alternating automata");
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auto aut_ = std::const_pointer_cast<twa_graph>(aut);
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acc_cond old = aut_->acc();
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bool res = generic_emptiness_check_main(aut_, nullptr);
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aut_->set_acceptance(old);
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return res;
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}
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twa_run_ptr generic_accepting_run(const const_twa_graph_ptr& aut)
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{
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if (SPOT_UNLIKELY(!aut->is_existential()))
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throw std::runtime_error("generic_accepting_run() "
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"does not support alternating automata");
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auto aut_ = std::const_pointer_cast<twa_graph>(aut);
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acc_cond old = aut_->acc();
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twa_run_ptr run = std::make_shared<twa_run>(aut_);
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bool res = generic_emptiness_check_main(aut_, run);
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aut_->set_acceptance(old);
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if (!res)
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return run;
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return nullptr;
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}
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bool generic_emptiness_check_for_scc(const scc_info& si,
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unsigned scc)
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{
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if (si.is_accepting_scc(scc))
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return false;
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return is_scc_empty(si, scc, si.get_aut()->acc(), nullptr);
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}
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bool
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generic_emptiness_check_for_scc(const scc_info& si, unsigned scc,
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const acc_cond& forced_acc)
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{
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if (si.is_trivial(scc))
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return true;
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return scc_split_check(si, scc, forced_acc, nullptr, {});
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}
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}
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